| 完整稻秆卷压过程应力松弛试验 |
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| 引用本文： | 雷军乐,王德福,张全超,杨星,李利桥,李超.完整稻秆卷压过程应力松弛试验[J].农业工程学报,2015,31(8):76-83. |
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| 作者姓名： | 雷军乐 王德福 张全超 杨星 李利桥 李超 |
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| 作者单位： | 1. 东北农业大学工程学院，哈尔滨 1500302. 黑龙江职业学院工程学院，哈尔滨 150080,1. 东北农业大学工程学院，哈尔滨 1500303. 河南农业大学机电学院，郑州 450002,1. 东北农业大学工程学院，哈尔滨 150030,1. 东北农业大学工程学院，哈尔滨 150030,1. 东北农业大学工程学院，哈尔滨 150030,1. 东北农业大学工程学院，哈尔滨 150030 |
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| 基金项目： | 国家自然科学基金资助项目（51405076）；高等学校博士学科点专项科研基金资助项目（20124105110004）；黑龙江科技攻关项目（GC13B604） |
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| 摘 要： | 为深入研究完整稻秆在卷捆压缩过程中的流变特性,该文利用自制的钢辊式圆捆机卷压试验台进行了完整稻秆卷压过程应力松弛试验研究。选择稻秆含水率、草捆干物质质量、卷捆钢辊转速、稻秆喂入速度为试验因素,并以应力松弛时间和平衡弹性模量作为应力松弛特性评价指标,进行4因素5水平正交旋转组合试验。结果表明:完整稻秆卷压过程应力松弛模型可用1个Maxwell单元和1个弹簧并联组成的三元件方程表示;各因素对应力松弛时间贡献率排序依次为稻秆含水率、草捆干物质质量、稻秆喂入速度、卷捆钢辊转速;对平衡弹性模量贡献率排序依次为草捆干物质质量、稻秆含水率、稻秆喂入速度、卷捆钢辊转速;当稻秆含水率为65%、草捆干物质质量为17 kg、卷捆钢辊转速为257 r/min、稻秆喂入速度为1.6 kg/s时,应力松弛时间和平衡弹性模量可分别达最佳值17.08 s和4.01 k Pa。试验结果可为圆型打捆机对完整稻秆的卷压工艺优化及其压缩机理分析提供必要的理论与技术支持。
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| 关 键 词： | 流变 应力松弛 优化 完整稻秆 圆捆机 卷压过程 |
| 收稿时间： | 2015/1/28 0:00:00 |
| 修稿时间： | 3/1/2015 12:00:00 AM |
Experiment on stress relaxation characteristics of intact rice straw during rotary compression |
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| Lei Junle,Wang Defu,Zhang Quanchao,Yang Xing,Li Liqiao and Li Chao.Experiment on stress relaxation characteristics of intact rice straw during rotary compression[J].Transactions of the Chinese Society of Agricultural Engineering,2015,31(8):76-83. |
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| Authors: | Lei Junle Wang Defu Zhang Quanchao Yang Xing Li Liqiao and Li Chao |
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| Institution: | 1. College of Engineering, Northeast Agricultural University, Harbin 150030, China2. College of Engineering, Heilongjiang vocational college, Harbin 150080, China,1. College of Engineering, Northeast Agricultural University, Harbin 150030, China3. College of Mechanical and Electrical Engineering, Henan Agricultural University, Zhengzhou 450002, China,1. College of Engineering, Northeast Agricultural University, Harbin 150030, China,1. College of Engineering, Northeast Agricultural University, Harbin 150030, China,1. College of Engineering, Northeast Agricultural University, Harbin 150030, China and 1. College of Engineering, Northeast Agricultural University, Harbin 150030, China |
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| Abstract: | Abstract: In recent years, rice straw as a kind of renewable material is being used widely in China. The rheologic characteristics of crop straw have great effect on the power consumption, productivity and compression process of compressing equipment, as well as on the bale durability. At present, a lot of researches have been done by many domestic and foreign scholars on the compression rheologic characteristics, but the researches have been aimed at the rectangular baler instead of the steel-roll round baler, and the test materials are mainly concentrated on corn straw, wheat straw and alfalfa, which limit the development and application of the round baler for crop straw in China. Stress relaxation is an important phenomenon in the rheologic characteristics of straw. In order to deeply research stress relaxation phenomenon of intact rice straw during rotary compression under the round baler, a steel-roll round baler was used for rotary compression test in this paper. To timely monitor the force during rotary compression, the force testing device was developed. In experiments, moisture content of rice straw (12%-68%), dry material quantity of bale (15-23 kg), steel roll speed (222-318 r/min) and feeding speed of rice straw (0.4-1.6 kg/s) were chosen as experimental factors, which were at 5 levels. Stress relaxation time and balance elastic modulus were decided as the evaluation indices, and quadratic orthogonal rotatory combination design was used to analyze the effect of different factors. Through analyzing experimental data by Matlab 8.0, the stress relaxation model of intact rice straw during rotary compression could be expressed by three-element equation which was available through the parallel connection of one Maxwell unit and one spring. The regression equations of stress relaxation time and balance elastic modulus had been established respectively by using Design Expert software. Through variance analysis of regression equations for stress relaxation time and balance elastic modulus, the coefficients of determination (R2) for the models were 0.96 and 0.97 respectively, which indicated that the proposed model was agreeable with the practical condition, thus the proposed model could be used to predict the change of the stress relaxation time and balance elastic modulus during rotary compression. In addition, the relations between evaluation index and each single factor were shown in response surface. The results showed that: with the increase of moisture content of rice straw, both of stress relaxation time and balance elastic modulus decreased; with the increase of dry material quantity of bale, stress relaxation time decreased and balance elastic modulus increased; with the increase of steel roll speed, stress relaxation time and balance elastic modulus decreased and then increased; and with the increase of feeding speed of rice straw, stress relaxation time decreased and balance elastic modulus increased gradually. The contribution rate of each factor on stress relaxation time was as follows: moisture content of rice straw > dry material quantity of bale > feeding speed of rice straw > steel roll speed. The contribution rate of each factor on balance elastic modulus was as follows: dry material quantity of bale > moisture content of rice straw > feeding speed of rice straw > steel roll speed. When moisture content of rice straw was 65%, dry material quantity of bale was 17 kg, steel roll speed was 257 r/min and feeding speed of rice straw was 1.6 kg/s, stress relaxation time was 17.08 s and the balance elastic modulus was 4.01 kPa, which were the best results. The research provides theoretical and technical support for the process optimization of round baler, as well as the analysis of its compression mechanism. |
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| Keywords: | rheology stress relaxation optimization intact rice straw round baler compression process |
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